CHRIS MARSHALL

Prime Minister Theresa May has announced the UK terror threat level has been raised from severe to critical in the wake of the Manchester attack, meaning another atrocity is Britain is expected ‘imminently’.

In a televised statement from Downing Street, Mrs May said it was possible a “wider group of individuals” could have been involved in the Manchester Arena attack rather than just 22-year-old suicide bomber Salman Abedi.

Theresa May speaks from Downing Street on Tuesday evening.

Mrs May also announced that troops would be serving alongside police officers in towns and cities across the UK.

Children as young as eight were among the dead and injured after 22-year-old Abedi – Manchester-born, and of Libyan heritage – used a home-made device packed with nuts and bolts to ­target a pop concert.

Armed police are being deployed on the streets of Scotland and security for this weekend’s Scottish Cup Final is being reviewed.

Saffie Rose Roussos.

Mrs May said the terror threat level was increased after investigations revealed Abedi may not have acted alone.

“The work undertaken throughout the day has revealed that it is a possibility we cannot ignore that there is a wider group of individuals linked to this attack.

“This morning I said that the Joint Terrorism Analysis Centre, the independent organisation responsible for setting the threat level on the basis of the intelligence available, was keeping the threat level under constant review.

“It has now concluded, on the basis of today’s investigations, that the threat level should be increased for the time being from severe to critical.

Graphic locates the explosion at Manchester Arena. See story POLICE Explosion. Editable files available from PA Graphics

“This means that their assessment is not only that an attack remains highly likely, but that a further attack may be imminent.”

The Prime Minister said Operation Temperer - allowing military personnel to take to the streets - was now in force.

“This means that armed police officers responsible for duties such as guarding key sites will be replaced by members of the armed forces, which will allow the police to significantly increase the number of armed officers on patrol in key locations.

“You might also see military personnel deployed at certain events such as concerts and sports matches, helping the police to keep the public safe.”

Operation Temperer means soldiers could replace armed police at many sites, freeing them up for patrols in key areas.

The way that members of the armed forces are deployed will be a matter for police commanders.

Armed police on duty in Edinburgh on Tuesday.

She added: “The spirit of Manchester and the spirit of Britain is far mightier than the sick plots of depraved terrorists. That is why the terrorists will never win and we will prevail.”

The explosion at the Manchester Arena – the deadliest terrorist attack on UK soil since the 7/7 London bombings in 2005 – was timed to coincide with the end of a show by US singer Ariana Grande and has been described as an act of “sickening cowardice”.

Among the dead are eight-year-old Saffie Rose Roussos, the youngest known victim, and Georgina Callander, 18.

Laura MacIntyre, 15, from the Isle of Barra, was last night confirmed to be in a serious condition in hospital after her family had an agonising wait while she was listed as missing. Her friend Eilidh MacLeod, 14, remained unaccounted for.

Amid a fast-moving investigation yesterday, police said the man suspected of carrying out the attack was Abedi, 22, whose family is believed to have come to the UK from Libya.

Islamic State claimed responsibility for the attack, although its claim could not be immediately verified.

Mobile phone footage taken from inside the arena showed young fans, many of them holding pink balloons, run for cover and climb railings to escape after the explosion rocked the venue’s foyer.

Eyewitnesses spoke of seeing victims with serious injuries and having to pull pieces of shrapnel from the bodies of survivors.

Homeless man Chris Parker, 33, who was in the foyer to beg, said: “As people were coming out of the glass doors I heard a bang and within a split second I saw a white flash, then smoke and then I heard screaming.

“There were nuts and bolts all over the floor. People had holes in their back.”

Another fan, Majid Khan, 22, described the blast and ensuing panic. He said: “It was one bang and essentially everyone from the other side of the arena where the bang was heard from suddenly came running towards us as they were trying to exit.”

Oliver Jones, 17, who attended with his 19-year-old sister, said: “The bang echoed around the foyer of the arena and people started to run. I seensaw people running and screaming towards one direction, and then many were turning around to run back the other way.”

As details of the victims began to emerge, armed officers from Greater Manchester Police (GMP) raided an address in the city’s Elsmore Road where Abedi, a student at Salford University, was registered as living.

And a 23-year-old man was arrested elsewhere in the city by plain-clothes police officers and held in connection with the bombing. Describing the day’s activities, Chief Constable Ian Hopkins said: “Part of this response has seen us arrest a 23-year-old man in connection with the attack and we have also carried out two warrants, one in Whalley Range and one in Fallowfield that included a controlled explosion to enable safe entry.

“We understand that feelings are very raw right now and people are bound to be looking for answers. However, now, more than ever, it is vital that our diverse communities in Greater Manchester stand together and do not tolerate hate.”

“I can confirm that the man suspected of carrying out last night’s atrocity has been named as 22-year-old Salman Abedi. However, he has not yet been formally identified and I wouldn’t wish, therefore, to comment further. The priority remains to establish whether he was acting alone or as part of a network.”

All campaigning for next month’s general election was yesterday cancelled following the attack, including the leaders debate in Scotland.

First Minister Nicola Sturgeon said Police Scotland had “significantly” increased the number of armed officers on patrol following the attack.

The force will review security for all events scheduled to take place in Scotland in the next 14 days, including the Scottish Cup Final at Hampden on Saturday.

The First Minister said four of the six people who “presented at hospitals here in Scotland” in the wake of the attack had been discharged. Two were last night still being treated, but their injuries are not thought to belife-threatening.

Ms Sturgeon told MSPs at Holyrood: “My thoughts, those of this Parliament, indeed all of the people of Scotland, are with those who have lost loved ones or sustained injuries in this dreadful atrocity.

“There can be nothing more cowardly than attacking children and young people enjoying a fun night out.

“Across Scotland today we stand in solidarity with the people of Manchester, a great city with which so many of us here in Scotland share a great affinity.”

Last night it was confirmed that Isle of Barra schoolgirl Laura MacIntyre was being treated in hospital for serious injuries.

The families of the 15-year-old, and her friend Eilidh MacLeod, 14, made desperate appeals when the girls failed to get in touch with family after the explosion.

Angus MacNeil, who has represented the island as SNP MP since 2005, said the older girl was being treated in hospital in Manchester.

“Laura is alive in hospital and is in a serious condition,” he said.

“We are obviously still extremely worried about Eilidh. We have no news at the moment.”

As thousands gathered in sombre defiance for a vigil in Manchester city centre, tributes were paid to those who lost their lives.

The death of eight-year-old Saffie was described by her headteacher as “heartbreaking”. Chris Upton, of Tarleton Community Primary School, in Leyland in Lancashire, said: “Saffie was simply a beautiful little girl in every aspect of the word.”

Teenager Georgina Callander, who was studying health and social care, was named by her college, Runshaw College in Lancashire.

Tributes were also paid to 26-year-old John Atkinson from Bury, who was named by friends on Facebook.